Biochemical tests for blood are widely carried out as means for diagnosing the conditions of human's health. It is difficult to measure the kinds or concentrations of constitutive components in blood, such as metabolites, proteins, lipids, electrolytes, enzymes, antigens and antibodies, using whole blood, and thus they are normally measured using plasma or serum which is obtained by centrifuging whole blood as a sample.
The centrifugation requires times and efforts, and a centrifugation method requiring a centrifuge is unsuitable for cases where a particularly small quantity of samples are to be processed urgently or for on-site tests. Further, the quantity of serum or plasma obtained by the centrifugation is smaller than the quantity of blood which has been obtained by blood collection.
Thus, as blood component analytical methods which are not affected by cell components such as hemocytes even when whole blood is used as a sample, blood component analytical methods such as those disclosed in Japanese Published Patent Applications No. Sho 57-53661 and No. Hei. 8-54387, employing a hemocyte separation method by which blood is exuded using glass fiber filter paper having an average diameter of. 0.2-5 μm and a density of 0.1-0.5 g/cm3 thereby separating plasma or serum, or a blood component analytical method such as one disclosed in Japanese Published Patent Application No. Hei. 9-196908, employing a blood regulation method by which an aqueous solution of amino acid or inorganic salt is mixed with whole blood and thereafter hemocyte components are filtered, thereby avoiding clogging of filtered materials due to hemocytes, and a larger quantity of plasma or serum components are obtained using a smaller quantity of blood have been examined.
Further, a method as disclosed in Japanese Published Patent Application No. Hei. 9-72904, by which blood is hemolyzed by a surfactant carried on a test strip and then a sample solution is developed on the test strip using a development solution has been examined.
It is true that the method employing the glass fiber filter paper of the prescribed density improves the hemocyte separation efficiency, but it takes quite a long time to separate hemocytes almost completely. Thus, the measurement cannot be performed quickly, and further not only a large quantity of blood is required to obtain a quantity of samples that is necessary for the test, but also the blood viscosities or hematocrit values differ among individuals so that the separation power has individual differences and thus the measurement accuracy is quite low. Further, it requires special filter paper, thereby being costly.
In the method by which an aqueous solution of the prescribed concentration of mineral salt or amino acid is added to whole blood and then hemocyte components are filtered, the efforts for hemocyte separation by the centrifugation are omitted, but the operation of previously adding an additive liquid to the blood to be processed is so complicated that it lack the simplicity as well as the measurement takes much time.
Further, in the method of previously hemolyzing blood, the basic principle of hemolysis is destroying a bilayer lipid membrane in the cell membrane of the hemocyte using a surfactant or a hemolyzer such as saponin, and crushing a hemocyte cell to pieces. In the case of a very small quantity of blood, the development solution is added after the hemolysis is performed, thereby enabling development on a chromatographic device. However, when the development solution is not used, the development layer is clogged with cell pieces, so that the collected blood sample cannot be developed without the development solution.
The present invention is made to solve the above-mentioned problems and has for its object to provide a one-step biosensor and a blood component analytical method, which can perform a high-accuracy blood component analytical method easily and quickly, with less expenses and without the need to previously carry out any processing for blood or the need for a development solution for developing a sample solution, even when a sample is whole blood.